Embodiments of the invention relate generally to automated angiogram analysis, and more specifically, to detecting coronary stenosis through spatio-temporal tracking.
Cardiovascular disease (CVD) results in more death and disability in both males and females in all western societies than any other disease category, accounting for one third of all deaths in the United States in 2007. Any occlusion of these arteries can impact heart function leading to effort intolerance with exertion provoked chest symptoms, heart attack, permanent impairment of heart muscle function, and sudden death.
The “gold standard” diagnostic test for CAD is the coronary angiogram. A coronary angiogram involves placing plastic catheters into the arterial system and injecting iodinated contrast solution into the coronary blood flow, to obtain a silhouette of the coronary arterial wall. The angiographic images are typically recorded at 15 or 30 frames a second, providing a motion picture of the flowing blood and contrast mixture to permit the identification of segmental coronary narrowing or blockage attributable to coronary stenosis, which is a condition in which a coronary artery becomes tapered and backed up with materials like fat or cholesterol.
In general detection of vessels and coronary stenosis in X-ray angiography data is difficult due to the low contrast between vessels and surrounding tissue, as well as large intensity gradients within the image. Interpretation of coronary angiograms is nearly always performed by visual estimation of the severity of narrowing in the diseased coronary artery. In addition, the curvilinear cylindrical structure of an artery and the irregular and often eccentric remaining lumen through the diseased segment make accurate visual detection of stenosis difficult. Often, spurious dye and imaging artifacts can give a false appearance of stenosis in these sequences. To resolve such cases, clinicians watch the angiograms in loops exploiting the fact that a real stenosis will persist in each image frame through time.